At the present time, it appears that shortages of conventional forms of energy, particularly oil, have become critical. Much effort has been devoted to finding alternate sources of energy. Most energy sources suffer from drawbacks. Some are limited as to the amounts available, and when a particular material has been used it is gone forever. They are not available to all nations. Some have created ecological problems. It is not known how to handle some energy sources safely or dispose of their wastes safely. Most, with the exception of gravity, wind and water, are not forces by themselves. They can do nothing unless something is done to them.